The present invention relates to an improved skateboard having a platform and a single row of rollers mounted on the undersurface of the platform for rollably supporting the platform on a relatively hard surface, such as hard ground, a street or sidewalk, etc. A person may stand on the platform and propel it forwardly with the aid of poles, somewhat like the propelling motions in cross-country skiing.
U.S. Pat. No. 4,865,342 to Kong shows a skateboard comprising a platform, a front caster wheel, and a rear non-steerable wheel, and a friction brake pad behind the non-steerable wheel. The person stands with both feet on the platform, while thrusting two poles against a pavement surface, thereby propelling the board forwardly. The person can stop the skateboard by shifting his weight rearwardly on the platform to tilt the platform rearwardly to bring the brake pad into frictional engagement with the pavement surface. The poles serve as propulsion devices and also as steadying devices to prevent the person from falling off the platform.
The skateboard of this patent relies on two wheels for stability. With such an arrangement, the wheels have insufficient frictional contact with the supporting surface adequately to stabilize the skateboard, especially during turning maneuvers. A skateboard having a greater number of support wheels provides a greater degree of stability.
U.S. Pat. No. 5,125,687 to Hwang shows a skateboard in many respects similar to that of U.S. Pat. No. 4,865,342. The board has two additional outboard rollers located near opposite side edges of the board, i.e., spaced from the board centerline. The skateboard of this patent is inherently safer and more stable than the board of U.S. Pat. No. 4,865,342. However, the presence of the two additional rollers makes it more difficult to turn and maneuver the skateboard, because the additional rollers prevent the board from tilting in the transverse, side-to-side directions. When a person shifts his weight laterally (transversely) to execute a turning maneuver, the skateboard does not fully respond to the weight shift, and the skateboard is not easily turned.
U.S. Pat. No. 3,622,172 to Goodwin shows a roller type land ski adapted to support only one of a person's feet. The person uses two skis to ski down a sloping surface. Clamping devices are provided on each ski for attaching the ski to a person's ski boot. These land skis are apparently used in the manner of conventional winter snow skis.
In the land ski of the Goodwin patent, frictional resistances are overcome by a single row of rollers carried on the undersurface of each ski, and a frictional brake is carried at the rear end of each ski. The person can bring the brake into frictional engagement with the ground surface by shifting his weight rearwardly, thus to tilt the ski downwardly in a rearward direction,
There has existed a need for skateboards capable of effecting turning of rollers in response to a person's exertion of downward force on portions of the skateboard to provide better turning and maneuvering capabilities, and there has existed a need for effective shock-absorber means for absorbing impact energy upon skateboard rollers encountering bumps, obstructions, depressions, etc.